converting a petrol engine to LPG
Martyn Fagg
run on LPG?
My dad is about to buy a 20ft sports boat with about a 4L engine and he is
thinking about converting it from petrol to LPG. Does anyone know if it is
possible to do it yourself and how hard it is to convert.
If you do know can you let me know how to do it or a web-site that has
instructions.
Thanks in advance.
Martyn Fagg
boat @ martynfagg.co.uk
JDavis1277
order to have sufficient fuel for any range, at all, a lot of tankage is needed
for a 4 litre engine driving a 20 foot boat. Plus, the tankage must be capable
of containing the pressure of LPG.
No offense, but I don't believe you can get there from here. Furthermore, I
doubt the legality of the conversion in the UK.
Good luck,
Butch
Rod McInnis
Martyn Fagg wrote:
>
>
> My dad is about to buy a 20ft sports boat with about a 4L engine and he is
> thinking about converting it from petrol to LPG. Does anyone know if it is
> possible to do it yourself and how hard it is to convert.
>
This topic comes up from time to time. There are conversion kits that
make it not too difficult to convert *some* engines over to run on LPG.
The basic change is the carburetor, which must now deal with a vapor
instead of a liquid fuel. In concept, it is as simple as removing the
old carburetor, bolting the new one on, hooking up the hoses and away
you go.
In the past, the general conclusion to this thread is "why would you
want to do such a thing?"
The LPG tank is going to be heavy, much heavier than a tank that would
hold the equivalent amount of petrol. It will also want to be in a
cylindrical shape, as that is the best shape for withstanding the
pressure. You will have a really hard time replacing the existing
petrol tank with an equivalent sized LPG tank.
Given that your LPG tank will be smaller, your range will be reduced
as a result. Now you enter another problem: Where do you go for a
refill?
A petrol tank you can refill from any marina, or from portable cans.
An LPG tank can only be refilled at an LPG station. I don't know about
the UK, but there are not many of those along the water here in the US.
Many marinas sell LPG, but the fill station is NOT on the dock, so you
have to carry your tank to shore. Not a problem for the 20 pound
portable tanks, but you are not going to carry a 20 gallon tank around.
There is also a safety concern. LPG is heavier than air, and will
collect in the bottom of a boat. If the carburetor malfunctions, the
LPG gas will flood the boat, and create a major explosion hazard. On a
petrol engine, a malfunctioning carburetor may flood the engine out, but
it won't continue to allow fuel to spill out (or at least not with a
mechanical fuel pump).
I believe that there will be small reduction in horsepower when
converting to LPG. Combined with the added weight, reduced range and
incredible hassle, this conversion just doesn't make sense.
Rod McInnis
M DeMetz
effect that:
1. LPG Weight was less per gallon of product. ( I got the impression that it
sort of compensated for the pressure tank (aluminum)).
2. LPG produced mor BTUs per gallon ( Or maybe it was pound ) than petrol.
3. You needed to change the timing for LPG. ( Retard I believe ).
4. The engin oil will thicken as you build hours. ( There are much fewer
contaminants getting past the rings ).
The reality in the application I did ( were 2 very identical dump trucks, they
were surplus with both systems ). I got one to run on petrol and the other to
run on LPG.
The LPG truck gave very little trouble compared to the petrol unit. Started
ran and most of all the cost of operation was about 25 to 30 % less than the
petrol unit.
We called a delivery truck every other day to top it off on the job site. Very
convenient at the time. I would assume the same could be don as long as the
boat could get close engulf to where the delivery truck could get to.
It is an interesting idea. I have a house boat that already has LPG for
cooking and heating. Increasing the tankage would be the biggest problem.
Back when I red the article there had not been a tank rupture from a road
accident. ( Not a bulk carrier ).
Mike
****************************
JDavis1277
Interesting comments.
Tankage for a 20 footer remains the major problem as well as the safety issues.
I doubt it can be done legally in the UK. I agree with Rod on this question.
It just doesen't make sense.
Probably not practical to have a truck make an LPG delivery to the marina.
More likely the 20 footer would be trailerable.
I'm a bit of a gadget freak and techno freak but I would not seriously consider
LPG for boat fuel, particularly in a small fast boat. I mean, what's the
point???
Butch
Mike wrote: >I don't know about boats but the book I red several years ago
Carl G. Craver
any LPG tanks must be such that, in the event of a leak at the tank, all the
fumes will vent overboard.
In addition to installing new tanks, you would have to have them in a
separate
compartment that is vented overboard.
Carl G. Craver
Evinru...@home.com
JDavis1277 <jdavi...@aol.com> wrote in message
news:20000124191512...@ng-fm1.aol.com...
K.Smith
<mar...@freenetname.co.uk> wrote:
Martyn,
The engine conversion is the same as in autos (mostly
Impco or OHG converters & mixers, re-arranged spark timing etc.).
The LPG tanks are stainless steel again as used in auto
conversion. (the stainless ones are very thin walled & light,
still heavier than a pressed metal tank but comparable to
fabricated stainless boat fuel tanks)
The tanks are usually mounted in the open where they are
self & well ventilated.
Here we have water taxis (20 to 25ft) that are LPG
powered, the stainless tanks are mounted at the rear of the
cockpit between the passenger area & the OBs.
Usual LPG safety standards apply, even for fare paying
passenger licensed craft.
Before the flood starts ;-) yes I did say "OBs" & yes
they are "normal" 2 strokes not Hondas etc. The finer details of
the conversion I'm not up on but just looking it seems as
expected with the gas mixer located ahead of the carbs. There
seems to be enough heat from the water telltale to run the
converter (at least up to the 115 HP or so that I've seen) & the
oil injection is modified (no petrol to mix with) to ensure
direct injection. (The standard Yamaha system is about right,
injecting the oil into the throats downstream of the carbs & not
into the fuel ahead of the carbs like Merc. I'm not allowed to
say VRO but obviously it's not suitable.....;-))
They claim to save much on fuel, but power is clearly
down a fair bit.
These 2 stroke OB conversions were well publicised in the
mid 80's & I'm not really sure why they never seemed to progress
past a few high use commercial applications.
Karen
>Does anyone know how hard it is to convert a petrol engine, on a boat, to
>run on LPG?
>
>My dad is about to buy a 20ft sports boat with about a 4L engine and he is
>thinking about converting it from petrol to LPG. Does anyone know if it is
>possible to do it yourself and how hard it is to convert.
>
>If you do know can you let me know how to do it or a web-site that has
>instructions.
>
Joel Frahm
(JDavis1277) writes:
>Mike,
>
>Interesting comments.
>
>Tankage for a 20 footer remains the major problem as well as the safety
issues.
> I doubt it can be done legally in the UK. I agree with Rod on this question.
>It just doesen't make sense.
>
>Probably not practical to have a truck make an LPG delivery to the marina.
>More likely the 20 footer would be trailerable.
>
>I'm a bit of a gadget freak and techno freak but I would not seriously
consider
>LPG for boat fuel, particularly in a small fast boat. I mean, what's the
>point???
>
>Butch
The boats on the Riverwalk in San Antonio use LPG and little (Yamaha?)
outboards. They are very clean and quiet, and I expect little maintenance
is required. I'm told in the UK, LPG is more viable as a motor fuel for
boats due to cost. Other benefits I can think of include longer engine
life (less startup wear, less oil breakdown) and fewer fuel system
problems. In the UK, repowering might be expensive enough to make
increased engine life worth considerable effort. I'm given to understand
that incorrect fuel mixture and incomplete burn will shorten engine life
due to gas contamination of the oil. EFI is a big help but a motor fuel
that is more oil friendly would also. I believe also that LPG burns
cleaner so less harmful byproducts go south into the crankcase too.
Plus, the fuel system is simple and reliable. If you have (liquid) fuel,
you have fuel pressure. Filtering should be no problem. Propane carbs
are simple and can even have a gasoline carb (used as a throttle plate)
so dual fuel is no problem. Storing the engine for long periods would
be easy since the propane would not need to be stabilized nor would it
evaporate in the carb and leave crud behind. If I had a little cabin
in the northwoods with a boat I used for a few weekend trips and then
stored for nine months, an LPG four-stroke outboard powered boat would
be great!
Tankage is a problem but for short trips maybe not a big problem.
Manageable. If you had a home liquid propane tank you could refill
the boat from the house tank, even. I believe 20 lbs of propane
is comparable to three gallons of gas so a 100 pound propane tank
would be like having 15 gallons of gas. Not a great deal of fuel
but perhaps enough depending on what you are doing.
-Joel Frahm
Nick Smeltzer
writes
> Given that your LPG tank will be smaller, your range will be reduced
>as a result. Now you enter another problem: Where do you go for a
>refill?
>
> A petrol tank you can refill from any marina, or from portable cans.
>An LPG tank can only be refilled at an LPG station. I don't know about
>the UK, but there are not many of those along the water here in the US.
>Many marinas sell LPG, but the fill station is NOT on the dock, so you
>have to carry your tank to shore. Not a problem for the 20 pound
>portable tanks, but you are not going to carry a 20 gallon tank around.
Petrol is scarcer than you may think around UK marinas and virtually
non-existent around Scottish coasts. LPG is springing up all over the
South Coast. It is promised on all major forecourts by 2001.
>
> There is also a safety concern. LPG is heavier than air, and will
>collect in the bottom of a boat. If the carburetor malfunctions, the
>LPG gas will flood the boat, and create a major explosion hazard. On a
>petrol engine, a malfunctioning carburetor may flood the engine out, but
>it won't continue to allow fuel to spill out (or at least not with a
>mechanical fuel pump).
Petrol is heavier than air too! An LPG installation makes your boat
safer because of the hydrocarbon sensors fitted that otherwise wouldn't
be fitted on most small boats (unless you manually added them).
>
> I believe that there will be small reduction in horsepower when
>converting to LPG. Combined with the added weight, reduced range and
>incredible hassle, this conversion just doesn't make sense.
No, no reduction at all if the engine is tuned correctly. In fact
engines tuned purely for LPG have slightly higher horse power.
Combined with increased engine life and decreased engine wear. Combined
with *massive* savings in the UK. Petrol is 75-80p per litre, LPG is 33p
per litre - that is less than half price!
The disadvantage is range as you stated. MPG is about 20% reduced on
LPG. Extra weight applies, but only really if you leave the original
tank in.
We have 6 LPG cars at work so I can vouch for them at least and I would
say that if there was a filler local to you then seriously look into
it..
HTH, Nick
--
Nick Smeltzer
ni...@greenhse.demon.co.uk (home)
nsme...@groundwork.org.uk (work)
JDavis1277
LPG can be used (obviously since it is used) in boats. IMO it is only useful
in small displacement hull/speed open boats with outboard power. Not that it
can't be used in high speed planing hulls with large inboard engines. Just
that, IMO, it is not very practical in those applications, gaoline prices in
the UK not withstanding.
The original question concerned a 20 foot boat with a four litre gasoline
engine. To me, that translates to a planing boat. Power required to drive a 20
foot displacement hull craft would probably be in the 10 or fewer hp range.
In the instance of a 20 foot boat with a four litre inboard I can not concive
of a good reason to convert it to LPG other than for the fun of making it work.
Possibly for a ski boat with extra tanks aboard the tow vehicle it would be a
useful conversion, since the boat could be conveniently refuled from the tow
vehicle. I'm not sure I'd want a bunch of steel tanks full of LPG in the tow
vehicle, but to each his or her own.
Butch
Swpro3
to the pound) it is very very expensive to run my Fairline Sprint, it has a
Volvo 4.3l and is 23ft oal .Therefore the advantages of an LPG conversion are
obvious , it only costs £1.35 a gallon. Also the infrastructure is there for
LPG .It has just been installed on the fuel pontoon at our Marina. A freind
has just purchased a Sea-Ray 250 that had been converted to LPG and there is no
discernable loss in performance than on gas , and it even runs much quieter.
Swpro3
conversion i was suprised that none of them answered your question! It is
perfectly legal in the UK to convert your boat to run on LPG aslong as you do
not use it on inland waterways controlled by British Waterways who's Boat
Safety scheme prohibits this at the moment. A freind of mine has a Sea--Ray 250
with a 5.7L Mercruiser that runs very well on LPG it is actually quieter on LPG
than on petrol ,with as far as we can tell no noticeable loss in performance.A
company called LPG Marine seem to be at the forefront of the conversion work
with agents all over the UK . I hope soon to have my Fairline Sprint with a
Volvo 4.3 converted by our local agent at Pwhelli marina , where we also have
LPG on the fuel pontoon and at 28p per litre the savings are incredible.If you
have any other questions i would be happy to help.
JDavis1277
I believe what you've told us is that a boat in the UK can be legally operated,
but not on inshore waters.
I guess the 20 footer with the 4 litre inboard engine is then a good candidate
for operating offshore?? The captain had better choose his days carefully and
be an excellent helmsman. I'm a yank but my wife is from the Isle of Wight and
we have made numerous crossings of the Solent on nice days as well as foul. I
have yet to see a day on the Solent when I would be comfortable piloting a 20
foot power boat.
Butch
Nick Smeltzer
waterways, what it doesn't allow is dual fuel systems, ie boats that can
run on either petrol or LPG.
You are legally allowed to convert to LPG yourself, but you will be
prevented from filling at any of the commercially operated filling
stations unless your conversion is certified.
Nick
In article <20000201150540...@ng-ck1.aol.com>, Swpro3
<swp...@aol.com> writes
>Hi Martyn, having just read some of the replies to your enquiry about lpg
>conversion i was suprised that none of them answered your question! It is
>perfectly legal in the UK to convert your boat to run on LPG aslong as you do
>not use it on inland waterways controlled by British Waterways who's Boat
>Safety scheme prohibits this at the moment. A freind of mine has a Sea--Ray 250
>with a 5.7L Mercruiser that runs very well on LPG it is actually quieter on LPG
>than on petrol ,with as far as we can tell no noticeable loss in performance.A
>company called LPG Marine seem to be at the forefront of the conversion work
>with agents all over the UK . I hope soon to have my Fairline Sprint with a
>Volvo 4.3 converted by our local agent at Pwhelli marina , where we also have
>LPG on the fuel pontoon and at 28p per litre the savings are incredible.If you
>have any other questions i would be happy to help.
--
Nick Smeltzer
<jdavi...@aol.com> writes
>Thanks for the information.
>
>I believe what you've told us is that a boat in the UK can be legally operated,
>but not on inshore waters.
>
>I guess the 20 footer with the 4 litre inboard engine is then a good candidate
>for operating offshore?? The captain had better choose his days carefully and
>be an excellent helmsman. I'm a yank but my wife is from the Isle of Wight and
>we have made numerous crossings of the Solent on nice days as well as foul. I
>have yet to see a day on the Solent when I would be comfortable piloting a 20
>foot power boat.
No, British Waterways run some rivers and all the canals. These are
where dual fuel boats are not allowed. They can be operated on lakes and
lochs without any worries. For info, BW are reviewing their policy on
the use of dual fuel.
Nick Smeltzer
<cu...@ici.net> writes
>Any company who builds gaseous fueled generators or forklifts would be able
>to sell you the parts. One large caution. LPG or Propane is heavier than
>air. It will end up in the bilge and may cause a very bad explosion. The LPG
What, and petrol isn't?
--
Nick